Cellular rubber profile, particularly sealing profile for the sealing of two components which cooperate with one another

ABSTRACT

A cellular rubber profile for the sealing of two components which cooperate with one another is disclosed. The profile has a black base structure and a non-black overlay structure which is co-extruded with the base structure. The overlay structure overlies the base structure in the manner of a cap. Opposite the overlay structure the profile has a foot portion with lateral protuberances.

FIELD OF THE INVENTION

The invention relates to a cellular rubber profile, and particularly toa sealing profile for the sealing of two components which butt againstone another.

BACKGROUND OF THE INVENTION

From the practice which is described in the journal “Kautschuk+GummiKunststoffe” (Dr. Alfred Hufthig Verlag GmbH, Heidelberg, Germany) No.1/91, article entitled “Elastomer-sealing systems in motor vehiclebodywork”, paragraph 5.1.3, it is known, for the sealing of diffusionplates relative to a lamp housing to use black cellular rubber sealingcords which are trapezoidal, oval or round in cross-section and whichare assembled into a ring from an EPDM extrusion profile. In addition tothis, cellular rubber profiles are used in a multiplicity of ways, interalia as buffers for abutting edges. In practice, such black cellularrubber profiles are frequently perceived to be aesthetically annoying.

One such cellular rubber profile is known from DE 91 06 181 U1. Itconsists throughout of the same (black) cellular rubber and comprises aprofile foot, a main portion, a profile head and two hollow chambersextending therethrough. The semicircular profile head is provided withcontinuous sealing ribs which extend radially outwards when the profilehead is unstressed.

From GB 1 545 511A, FIG. 10, it is known per se to apply, bycoextrusion, a thin, differently colored covering layer of veryexpensive PVC/nitrile polymer or HYPALON (R.T.M.) polymer to the freeouter surface of a trim profile which is U-shaped in cross-section andmade from inexpensive EPDM or similar polymers with up to 60% fillersand embedded reinforcement. From one limb of the trim profile can extenda tubular sealing profile which can consist for example of closed cellsponge rubber and which after its vulcanization must be fixed to thetrim profile in a separate manufacturing step.

From U.S. Pat. No. 4,513,044, FIGS. 3 and 4, it is known per se tocoextrude a trim profile which is U-shaped in cross-section and of blacksolid rubber, a tubular sealing profile of black sponge rubber extendingfrom one limb of the trim profile, and a layer of differently coloredsolid rubber overlying a part of the outer surface of the trim profileand of the sealing profile.

U.S. Pat. No. 5,087,488 shows as known per se a trim strip which iscoextruded from a basic material of a first, cheap thermoplasticmaterial, such as PVC or PE for example, and a differently coloredcovering layer of a second, more expensive thermoplastic material, forexample PP.

It is the object of the invention to provide an aesthetically attractivecellular rubber profile which also fulfills its technical functionsreliably, i.e. for example sealing or shock-absorbing.

This object is achieved in accordance with the invention by a cellularrubber profile comprising a black base structure and a non-black overlaystructure co-extruded with the base structure.

SUMMARY OF THE INVENTION

According to the invention, a cellular rubber profile is provided whichis coextruded as a duplex profile such that it has a black basestructure and a non-black overlay structure which is formed in one piecewith the base structure. While the black base structure defines theprofile in terms of its basic technical functions, the non-black overlaystructure, which can be standardized for example according to RALcolors, is decisive in terms of the aesthetic appearance of the cellularrubber profile. In this connection, it is particularly to be noted thatthe carbon black particles used for the manufacture of black cellularrubber are very extensively researched in terms of their performance incellular rubber, and consequently are reliably controllable with goodavailability and low cost. Colored particles on the other hand do notfurnish the desired technical properties and in addition arecomparatively expensive.

Preferably, the average thickness of the layer of the overlay structureamounts to 1.0 mm to 3.0 mm, particularly 1.5 mm. With a layer of suchthickness, the compression properties of the complete cellular rubberprofile in the depth direction of the cellular rubber profile are onlychanged to a trifling extent, so that the cellular rubber profilebehaves virtually in the same way as the known black cellular rubberprofiles, although it comprises an attractive colored overlay structure,for example cream-white, for use in headlamp housings.

Preferably, the cellular rubber profile is constructed in the manner ofa sealing profile and comprises a sealing portion and a foot portionprovided with lateral retaining surfaces on the side which lies oppositeto the sealing surface and which is connected to the sealing portion byway of a yieldingly flexible linking portion. This construction permitsthe sealing profile on the one hand to be mounted and retained in anoptimum manner and on the other hand gives optimum sealing, since theyieldingly flexible linking portion prevents dimensions and settingschosen for the sealing function from having a negative effect on themounting and retention of the profile. While it is unfavorable, for thesealing function, strongly to compress the sealing rubber in the fittingof the profile into a mounting groove of a lamp housing, it isnevertheless necessary for the retaining function to achieve, at leastregionally, a high retaining force by means of a large compression. Inthis connection it has proved to be particularly advantageous that thebasic structure, which comprises the foot portion, the linking portionand a large part of the sealing portion, is black and consequently canbe implemented with good mechanical properties.

The yieldingly flexible linking portion additionally has the advantagethat the sealing surface which faces the closure glass does not tilt iffor example the mounting groove characterized as a sealing bed isfinished off in an irregular or non-uniform manner. The yieldinglyflexible linking portion offers the possibility that the sealing portionmatches itself well both to the sealing bed and to the closure glasswithout at the same time having to sacrifice a reliable retention of theprofile. With the use of the sealing profile according to the inventionwith complex geometrical structures, which can have sections runningaway from the plane of the closure glass, an adhesive is no longernecessary. Thus, not only is the cost of fitting reduced, but it alsofacilitates a subsequent recycling according to type. There is no dangerthat the sealing profile could fall out of the sealing bed.

Preferably, the foot portion of the sealing profile comprises at leastone resilient retaining strip with a retaining protuberance whichprojects, in the unmounted state, laterally beyond the plane of thecorresponding contact surface of the sealing portion of the sealingprofile. This resilient retaining strip, upon mounting, is more stronglycompressed than the sealing portion, so that a high retaining force isachieved. The resilient retaining strip should be so formed that in theevent of a tensile force which is so directed that it tends to pull thesealing profile from the sealing bed, a withdrawal of the sealingprofile would only be possible by doubling the resilient retaining stripover.

Preferably, the foot portion is formed to be substantially symmetricalin relation to the central plane which extends in the direction of thelength of the profile and transversely to the sealing surface. Thus, themounting is facilitated, since a control of the profile on itslengthwise orientation becomes superfluous.

The mounting is facilitated if the lateral contact surfaces have aninclination to the central plane of 2° to 10°, preferably 4°, more thanthe angle of the corresponding wall sections of the mounting grooverelative to its central plane, and if the end regions of the sealingportion adjacent to the foot have a smaller width than the spacing ofthe corresponding, opposing wall sections of the mounting groove. Withsuch a dimensioning, the sealing profile can easily be pushed into themounting groove right up to the base, even if manufacturing tolerancesand unevenness of the mounting groove are present. Thanks to the stronginclination of the lateral contact surfaces of the sealing portionvirtually self-fitting into the sealing profile. In addition to this, acompensation volume is made available, so that the sealing portion, ascompared with known sealing cords, has a small pre-deformation andconsequently better sealing properties after its fitting into themounting groove.

In order to ensure a good sealing effect, the sealing portion shouldhave a width in comparison with the width of the mounting groove in theregion of the contact surfaces which is less than 20% greater,preferably less than 10% greater, than the width of the mounting groovein this region. Thus, there is maintained a high capacity fordeformation of the sealing profile in the region of the sealing portion.

In order to protect against the infiltration of moisture, according to apreferred embodiment of the invention, the foot portion has a sealingnose on the side which lies opposite the sealing surface. This sealingnose should be formed as a rib with side walls inclined to the centralplane and with a rounded hump, so that a deformation of the sealing noseis easily possible and therefore manufacturing tolerances in the bottomof the mounting groove do not have a negative effect on the position ofthe sealing surface which faces the closure glass.

Further advantageous embodiments and developments of the invention areset out in the subsidiary claims, as well as being shown in theaccompanying drawing in conjunction with the following description. Inthe drawing:

FIG. 1 is a cross-section through a preferred embodiment of a cellularrubber profile in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The cellular rubber profile 2 shown in FIG. 1 is coextruded as a duplexstrand profile and comprises a base structure 4 of black cellular rubberas well as an overlay structure 6 of cellular rubber which is coloredcream-white. The cellular rubber profile 2 is formed as a sealingprofile 10 having a sealing portion 12, a linking portion 14 and a footportion 16.

The sealing portion 12 is so shaped that it has a depth of about 65% ofthe depth of the complete sealing profile 10 in the cross-section takenalong the center plane 22 of the sealing profile 10. Lateral contactsurfaces 24, 26 of the sealing portion have an angle of inclinationrelative to the center plane 22 of from about 5°. By this means and byrounded shoulders 28, 30 in the transition zone from the sealing portion12 to the linking portion 14, a fitting into place of the sealingportion 12 during the mounting of the sealing profile 10 is facilitatedand a tilting of the sealing surface 32 is substantially prevented. Thelayer thickness of the overlay structure 6 amounts to 1.2 mm in theregion of the center plane and increases slightly towards the edges.

Annexed to the sealing portion 12 at the end thereof which lies oppositethe sealing surface 32 is the linking portion 14. The linking portionrepresents a narrowing which makes it much less in width than the widthof a mounting groove. At its narrowest place the linking portion 14 hasa width which corresponds to only about 38% of the maximum width of thesealing portion 12. Therefore, the linking portion is yieldinglyflexible, so that the position of the foot portion 16 which is annexedto the linking portion 14 remains without any influence on the positionof the sealing portion 12.

The foot portion 16 has a width which is greater by 100% than that ofthe linking portion 14 in the cross-section perpendicular to the centerplane 22. Protuberances 34, 36 of the foot portion 16 are formed asresilient anchor strips permitting, at least partially, a tiltingmovement. Thus, lateral retaining surfaces 38, 40 come into contact withthe mounting groove so that a withdrawal of the sealing profile 10 fromthe mounting groove would only be possible by doubling over the lateralprotuberances 34, 36.

What is claimed is:
 1. A cellular rubber profile comprising a black basestructure and a non-black overlay structure co-extruded with the basestructure, wherein the base structure and the overlay structure areformed in the manner of a sealing profile for the sealing of twocomponents which cooperate with one another, and wherein the overlaystructure overlies the base structure in the manner of a cap.
 2. Acellular rubber profile according to claim 1, wherein the overlaystructure has an average thickness between about 1.0 mm and about 3.0mm.
 3. A cellular rubber profile according to claim 1, wherein theoverlay structure has an average thickness of about 1.5 mm.
 4. Acellular rubber profile according to claim 1, wherein said twocomponents comprise a lamp housing which cooperates with a closureglass.
 5. A cellular rubber profile according to claim 1, wherein thebase structure has a hardness of 10 to 25 on the Shore A scale.
 6. Acellular rubber profile according to claim 1, wherein the base structurehas a hardness of about 20 on the Shore A scale.
 7. A cellular rubberprofile according to claim 1, wherein the base structure and the overlaystructure each have a mixed-cell pore structure with a closed skin.
 8. Acellular rubber profile according to claim 7, wherein the pores of theoverlay structure have an average pore size which is relatively smallerthan the average pore size of the pores of the base structure.